CIF 2.0 specification and API published

Public discussion forum for the CIF2.0 standard.

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Brian McMahon
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CIF 2.0 specification and API published

Post by Brian McMahon » Mon Jan 04, 2016 12:10 pm

Two papers in the current Journal of Applied Crystallography give a specification of an updated Crystallographic Information File format, and describe an accompanying application programming interface (API) and reference implementation. The CIF2.0 format was formally approved by the maintenance committee COMCIFS in August 2014, and the paper of Bernstein et al. (2016) ( represents the first formal publication of the new file format. The CIF API of Bollinger (2016) ( provides software developers with tools for using the new format, for validating the syntax of their files against the new standard, and for converting data files between old and new formats if required.

Since CIF was designed from the outset as an archival format, publishers and databases will continue to support the existing CIF1.1 format indefinitely. It is not expected that any existing CIF-writing software will need to change in the immediate future.

So what is the purpose of the new specification? It introduces a number of novel features, such as the Unicode character set to handle data internationalization, and complex data types which can make it easier to handle vector or matrix objects. A particular benefit is that it will allow relationships between data items to be defined using methods expressions in future CIF dictionaries, opening the way to more powerful automatic validation of the contents of a data file, and this is likely to be the first area in which the new format will be used. The timescale for applying CIF 2.0 features to the data files themselves will depend very much on the desire of individual communities to take advantage of the potential benefits of the new format.

We would encourage software developers with an interest in these new features to become familiar with the website, and consider signing up to the cif-developers mailing list ( or the new CIF2 forum

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